From: Gerhard Engleder <gerhard@engleder-embedded.com>
To: netdev@vger.kernel.org
Cc: davem@davemloft.net, kuba@kernel.org, edumazet@google.com,
pabeni@redhat.com,
Gerhard Engleder <gerhard@engleder-embedded.com>
Subject: [PATCH net-next 1/4] tsnep: Throttle interrupts
Date: Thu, 17 Nov 2022 21:14:37 +0100 [thread overview]
Message-ID: <20221117201440.21183-2-gerhard@engleder-embedded.com> (raw)
In-Reply-To: <20221117201440.21183-1-gerhard@engleder-embedded.com>
Without interrupt throttling, iperf server mode generates a CPU load of
100% (A53 1.2GHz). Also the throughput suffers with less than 900Mbit/s
on a 1Gbit/s link. The reason is a high interrupt load with interrupts
every ~20us.
Reduce interrupt load by throttling of interrupts. Interrupt delay is
configured statically to 64us. For iperf server mode the CPU load is
significantly reduced to ~20% and the throughput reaches the maximum of
941MBit/s. Interrupts are generated every ~140us.
Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
---
drivers/net/ethernet/engleder/tsnep_hw.h | 7 +++++++
drivers/net/ethernet/engleder/tsnep_main.c | 6 ++++++
2 files changed, 13 insertions(+)
diff --git a/drivers/net/ethernet/engleder/tsnep_hw.h b/drivers/net/ethernet/engleder/tsnep_hw.h
index 315dada75323..55e1caf193a6 100644
--- a/drivers/net/ethernet/engleder/tsnep_hw.h
+++ b/drivers/net/ethernet/engleder/tsnep_hw.h
@@ -48,6 +48,13 @@
#define ECM_COUNTER_LOW 0x0028
#define ECM_COUNTER_HIGH 0x002C
+/* interrupt delay */
+#define ECM_INT_DELAY 0x0030
+#define ECM_INT_DELAY_MASK 0xF0
+#define ECM_INT_DELAY_SHIFT 4
+#define ECM_INT_DELAY_BASE_US 16
+#define ECM_INT_DELAY_OFFSET 1
+
/* control and status */
#define ECM_STATUS 0x0080
#define ECM_LINK_MODE_OFF 0x01000000
diff --git a/drivers/net/ethernet/engleder/tsnep_main.c b/drivers/net/ethernet/engleder/tsnep_main.c
index 48fb391951dd..a99320e03279 100644
--- a/drivers/net/ethernet/engleder/tsnep_main.c
+++ b/drivers/net/ethernet/engleder/tsnep_main.c
@@ -39,6 +39,8 @@
#endif
#define DMA_ADDR_LOW(dma_addr) ((u32)((dma_addr) & 0xFFFFFFFF))
+#define INT_DELAY (64 / ECM_INT_DELAY_BASE_US)
+
static void tsnep_enable_irq(struct tsnep_adapter *adapter, u32 mask)
{
iowrite32(mask, adapter->addr + ECM_INT_ENABLE);
@@ -1298,6 +1300,7 @@ static int tsnep_phy_init(struct tsnep_adapter *adapter)
static int tsnep_queue_init(struct tsnep_adapter *adapter, int queue_count)
{
u32 irq_mask = ECM_INT_TX_0 | ECM_INT_RX_0;
+ u8 irq_delay = (INT_DELAY << ECM_INT_DELAY_SHIFT) & ECM_INT_DELAY_MASK;
char name[8];
int i;
int retval;
@@ -1316,6 +1319,7 @@ static int tsnep_queue_init(struct tsnep_adapter *adapter, int queue_count)
adapter->queue[0].tx = &adapter->tx[0];
adapter->queue[0].rx = &adapter->rx[0];
adapter->queue[0].irq_mask = irq_mask;
+ iowrite8(irq_delay, adapter->addr + ECM_INT_DELAY);
adapter->netdev->irq = adapter->queue[0].irq;
@@ -1336,6 +1340,8 @@ static int tsnep_queue_init(struct tsnep_adapter *adapter, int queue_count)
adapter->queue[i].rx = &adapter->rx[i];
adapter->queue[i].irq_mask =
irq_mask << (ECM_INT_TXRX_SHIFT * i);
+ iowrite8(irq_delay, adapter->addr + ECM_INT_DELAY +
+ ECM_INT_DELAY_OFFSET * i);
}
return 0;
--
2.30.2
next prev parent reply other threads:[~2022-11-17 20:15 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-17 20:14 [PATCH net-next 0/4] tsnep: Throttle irq, rotten pkts, RX buffer alloc and ethtool_get_channels() Gerhard Engleder
2022-11-17 20:14 ` Gerhard Engleder [this message]
2022-11-17 20:33 ` [PATCH net-next 1/4] tsnep: Throttle interrupts Andrew Lunn
2022-11-18 5:50 ` Gerhard Engleder
2022-11-19 1:24 ` Jakub Kicinski
2022-11-19 20:46 ` Gerhard Engleder
2022-11-17 20:14 ` [PATCH net-next 2/4] tsnep: Fix rotten packets Gerhard Engleder
2022-11-17 20:39 ` Andrew Lunn
2022-11-18 6:13 ` Gerhard Engleder
2022-11-19 1:26 ` Jakub Kicinski
2022-11-19 20:47 ` Gerhard Engleder
2022-11-17 20:14 ` [PATCH net-next 3/4] tsnep: Add ethtool get_channels support Gerhard Engleder
2022-11-17 20:14 ` [PATCH net-next 4/4] tsnep: Rework RX buffer allocation Gerhard Engleder
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